This invention relates to electrical connectors, and, more particularly, to separable electrical connectors suited for use under high-voltage conditions. Still more particularly, this invention relates to gas actuated high-voltage bushings having a contact mounted within a bore f or reciprocal movement within a bushing housing.
High-voltage separable connectors innerconnect sources of energy such as transformers to distribution networks or the like. The situations typically encountered in the connection and disconnection of electrical connectors and power distributions include "loadmake", "loadbreak", and "fault closure". Loadmake includes the joinder of male and female contact elements, one energized and the other engaged with a normal load. An arc of moderate intensity is struck between the contact elements as they approach one another and until joinder. Loadbreak includes the separation of such mated male and female contact elements, while they supply power to a normal load. Moderate intensity arcing again occurs between the contact elements from the point of separation thereof until they are somewhat removed from one another. Fault closure includes the joinder of male and female contact elements, one energized and the other engaged with a load having a fault, e.g., a short circuit condition. A substantial arcing occurs between the contact elements as they approach one another and until joinder, giving rise to the possibility of explosion and accompanying hazard to operating personnel.
The prior art teaches the use of materials which emit arc-quenching gas when subjected to arcing, thus adequately dissipating the moderate intensity of arcs which occur during loadmake and loadbreak. The problem situation is fault closure, in which considerably more arc-quenching gas and mechanical assistance are required to extinguish the arc. During fault closure, the gas generated pressures may be fifty times greater than such pressures during loadmake. With respect to fault closure, the prior art has relied upon the use of the arc-quenching gas to assist in accelerating the contact elements into engagement, thus minimizing arcing time.
A typical prior art electrical connector includes a bushing well connected to the transformer, a bushing insert which contains a female contact assembly connected to the well, and an elbow connected to a distribution line and containing a male contact to join an insert female contact in the female contact assembly. Because closure of the male and female contacts can occur under activated conditions or under fault conditions, the female contact is arranged to move within the insert to hasten the closure of the male and female contacts and thus extinguish any arc created. However, it is necessary to maintain electrical continuity during the travel of the female contact assembly. The connection between such female contact assembly and the remainder of the bushing insert must be flexible so as not to impede its movement but sufficient to carry the high currents in the circuit. Typical prior art devices include a female contact which has a piston that is moveable between a first and second position. Gas pressure which is generated by arcing during fault closure accelerates the female contact toward the male contact, thus hastening contact engagement and decreasing the time duration of the arc. Mechanisms for achieving these results have not always produced sufficient current paths causing the connectors to run hot, and interfering with proper operation of the distribution network and in the extreme, leading to the destruction of the bushing inserts.